There are many known methods for bulking or creping fabrics. One such method is set forth in U.S. Pat. Nos. 2,081,370 to Secrist and 3,837,344 to Patience. The method disclosed therein, though it provides bulk, does not provide a means for forming a fabric with a controlled pattern of corrugations. In addition, the patterns therein will be lost upon wetting.
U.S. Pat. No. 3,655,327 to Rollins discloses a method of creating a stretched characteristic in a woven fabric by creping in a manner known as "crimp interchange". In a preferred method set forth in that patent, some of the yarns comprise thermoplastic materials which are heat set after the crimp interchange to fix the creping and permanently establish the stretch characteristics of the fabric. This patent does not, however, set forth a method for making a fabric having a controlled pattern of corrugations as disclosed by the present invention.
In the typical methods for creping fabrics, the crepe pattern is established by after treatment of a finished woven fabric and not by the initial selection of yarns. In the present invention the corrugated final structure is created by and determined by the choice of patterns and of the yarns used to form the fabric.
Elastic rubber strands have also been incorporated into fabrics to pucker or bulk the fabrics. However, they are expensive and detract from the textile appearance and performance of the formed fabric. Texturized thermoplastic yarns have also been included in fabrics having a heat shrunk puckered bulk appearance. Alternating warp yarns yarns with varying degrees of shrink has also been used to produce fabrics with puffs, to develop depth in a fabric, and to create spacer fabrics wherein the low shrink yarns occupy the center portion of the final fabric, creating a space between the more highly shrink yarns, which move to the surfaces of the fabric. However, before the invention herein described no one has used a pattern of high shrink and low shrink texturized yarns to provide controlled corrugations or undulations in the entire fabric.